复习一下

对象

package main

import(
	"fmt"
)

type User struct{
	uid int
	name string
}

func main(){
	var user User
	fmt.Println(user)
}

协程

package main

import(
	"fmt"
)

func test(){
	fmt.Println("test func")
}

func main(){
	go test()
	fmt.Println("main func")
}

当你像我一样的写法，只会输出main func(go test()启动线程没有问题，问题是你的主线程执行完了后go test()其实协程还没有启动主线程就停止了，所以需要主线程来协助)

package main

import(
	"fmt"
	"time"
)

func test(){
	fmt.Println("test func")
}

func main(){
	go test()
	fmt.Println("main func")
	time.Sleep(time.Second*1)
}

mysql链接

驱动为:github.com/go-sql-driver/mysql

go get github.com/go-sql-driver/mysql

go get github.com/jmoiron/sqlx

A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.

 go env -w GOPROXY=https://goproxy.cn,direct

初始化数据库连接

package main

import(
	"fmt"
	_ "github.com/go-sql-driver/mysql"
	"github.com/jmoiron/sqlx"
	
)

func main(){
	DB, _ := sqlx.Open("mysql","root:YourMySQLPassWord@tcp(127.0.0.1:3306)/yourDataBaseName")
	//设置数据库最大连接数
	DB.SetConnMaxLifetime(100)
	//设置上数据库最大闲置连接数
	DB.SetMaxIdleConns(10)
	//验证连接
	if err := DB.Ping(); err != nil {
		fmt.Println("open database fail")
		return
	}
	fmt.Println("connnect success")
}

查询操作

不知道结构怎么定义的可查看mysql的对应数据库中 desc 表名;来查看

sqlx.Open(…).Query

package main

import(
	"fmt"
	"encoding/json"
	_ "github.com/go-sql-driver/mysql"
	"github.com/jmoiron/sqlx"
	
)

//struct序列化tag
type User struct{
	Uid int		`json:"uid"`
	Name string	`json:"name"`
	Pwd string	`json:"pwd"`
}

//数据库指针
var db *sqlx.DB

func init(){
	// database,err := sqlx.Open("mysql","root:qwertyuiop1@tcp(127.0.0.1)/learn_test")
	// if err != nil {
	// 	fmt.Println("open mysql failed,", err)
	// }
	// db = database
}

func main(){
	var user User
	DB, _ := sqlx.Open("mysql","root:password@tcp(127.0.0.1)/database")
	//设置数据库最大连接数
	DB.SetConnMaxLifetime(100)
	//设置上数据库最大闲置连接数
	DB.SetMaxIdleConns(10)
	//验证连接
	if err := DB.Ping(); err != nil {
		fmt.Println("open database fail")
		return
	}
	fmt.Println("connnect success")

	rows, e := DB.Query("select * from users")
	if e != nil {
		fmt.Println("query incur error")
	}
	for rows.Next(){
		e := rows.Scan(user.Uid, user.Name, user.Pwd)
		if e != nil{
			fmt.Println(json.Marshal(user))
		}
	}
	rows.Close()
}

sqlx.Open(…).Select()

package main

import(
	"fmt"
	// "encoding/json"
	_ "github.com/go-sql-driver/mysql"
	"github.com/jmoiron/sqlx"
	
)

//struct序列化tag
type User struct{
	Uid int		`db:"uid"`
	Name string	`db:"name"`
	Pwd string	`db:"pwd"`
}

//数据库指针
var db *sqlx.DB

func init(){
	database,err := sqlx.Open("mysql","root:password@tcp(127.0.0.1)/database")
	if err != nil {
		fmt.Println("open mysql failed,", err)
	}
	db = database
}

func main(){
	var user []User
	//sql := "select * from users"
	sql := "select * from users"
	err := db.Select(&user, sql)
	if err != nil {
		fmt.Println("exec failed, ", err)
		return
	}
	fmt.Println("select succ:", user)
}

添加

package main

import(
	"fmt"
	// "encoding/json"
	_ "github.com/go-sql-driver/mysql"
	"github.com/jmoiron/sqlx"
	
)

//struct序列化tag
type User struct{
	Uid int		`json:"uid"`
	Name string	`json:"name"`
	Pwd string	`json:"pwd"`
}

//数据库指针
var db *sqlx.DB

func init(){
	database,err := sqlx.Open("mysql","root:password@tcp(127.0.0.1)/database")
	if err != nil {
		fmt.Println("open mysql failed,", err)
	}
	db = database
}

func main(){
	sql := "insert into users(name,pwd) values(?,?)"
	value := [2]string{"wanwu","112233qw"}
	//执行sql语句
	r,err := db.Exec(sql,value[0],value[1])
	if err != nil {
		fmt.Println("exec failed",err)
		return
	}
	//查询最后一天用户ID，判断是否插入成功
	id,err := r.LastInsertId()
	if err != nil {
		fmt.Println("exec failed2",err)
		return
	}
	fmt.Println("insert succ",id)
}

事务

事务一般都是在insert的时候使用

sqlx.DB.Begin() 开始事务
sqlx.DB.Commit() 提交事务
sqlx.DB.Rollback() 回滚事务

conn,err := db.Begin()
if err != nil{
  fmt.Println("begin failed :", err)
  return
}
//执行插入语句
	r, err := conn.Exec("insert into users(name, pwd)values(?, ?)", "value1", "value2")

	if err != nil {
		fmt.Println("exec failed, ", err)
		conn.Rollback()      //出现异常，进行回滚操作
		return
	}

	id, err := r.LastInsertId()
	if err != nil {
		fmt.Println("exec failed, ", err)
		conn.Rollback()
		return
	}
	fmt.Println("insert succ:", id)
	conn.Commit() //提交

修改